In voyager the only control we have over exporting records to Libraries Australia is the "OK to export" button. The "NLA replace .. etc" is only concerned with downloading records from Libraries Australia. This is done when the 019 matches . The "OCLC replace ...etc" downloads matching against tha 010 ie LC nos.. The replace settings have nothing to do with exporting records although the wording suggest this is the case.
HOW TO IMPORT A GOOD RECORD FROM LA
1. Find a good record on LA
2. Copy the 019 field from the LA record.
3. Paste the 019 into the not so good Voyager record.
4. Save the 019 onto the poor record
5. Now "save to db" the good record and it will replace the bad one.
ditto for the 010